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Edison's non-toxic nickel-iron battery revived in ultrafast form

A team of chemists at Stanford have created a nickel-iron battery prototype that can charge and discharge in seconds using carbon nanostructures.

Usually, a nickel-iron battery is simply two electrodes -- of iron oxide and nickel(III)oxide -- suspended in potassium hydroxide solution. In a paper published in Nature Communications, the Stanford team (led by chemist Hongjie Dai) improved the nickel-iron battery's performance by growing nanocrystals of iron oxide on thin sheets of carbon, and nickel nanocrystals on carbon nanotubes. The result is a vastly increased surface area -- and a vastly increased charge rate.

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Nickel-iron batteries were first invented and patented by Swedish inventor Waldemar Jungner in 1899, and his design was improved upon by Thomas Edison in 1901. Edison's batteries were huge and clunky, but that didn't matter since their main use was in many of the first electric cars. However, as gasoline engines became cheaper, and more reliable, the batteries fell out of favour -- much to Edison's regret. That's because they can't store as much as other battery types of the same size, and the nickel-iron design charges and discharges very slowly (often taking many hours at a time). By the 1970s nickel-iron batteries were so unpopular in the US that the one company left manufacturing them shut down production.

On the plus side, nickel and iron are both cheaper and less toxic than the chemicals found in acid-based batteries. The batteries also last a long time (as long as 20 years when regularly charged and discharged), because nickel and iron dissolve very poorly in potassium hydroxide. This has left them popular as a backup power source for sites disconnected from main electricity grids (such as construction sites), or with companies who need to store excess energy generated by wind and solar power.

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ByJim Hill

So the development of a fast-charging, non-toxic battery with a huge lifespan (20 years relative to roughly five for a standard lithium ion battery) sounds like a big breakthrough. But it's not quite that fantastic yet, unfortunately, since its capacity per kg is still far below that of the lithium-ion batteries that power most electric vehicles -- and the new batteries now lose charge at about the same rate, meaning lifespan is no longer an advantage.

This opens the possibility of electric cars using a mix of battery types, with the faster charging nickel-iron batteries allowing faster acceleration and acting as an aid to regenerative braking, while the bulk of the car's fuel is kept in the larger capacity lithium-ion batteries. In other situations -- especially in a world with so many rechargable devices -- a non-toxic alternative to lithium-ion batteries holds much promise.

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However, it will have to compete with the team from Northwestern University, who in November 2011 claimed that they had managed to redesign the lithium-ion battery to charge ten times faster and last ten times longer.